In several cancers, the establishment of an immunosuppressive T cell response is correlated with a poor prognosis and disease progression.
Among the different cellular effectors involved in the establishment of immune tolerance, the CD4+ regulatory T lymphocytes subset (Treg) is specialised in the suppression of the other T cell (Tconv) as well as dendritic function. Said suppression may be correlated with a poor survival rate of patient suffering from cancer, especially from breast cancer.
It has been shown that large amounts of IL-10 and low quantities of IFNγ produced by CD4+ T cells are associated with reduced CD8+ T cell cytotoxic capacity, lower T cells proliferation and participate to monocytes differentiation into immunosuppressive M2c type macrophages, related to the Tumor Associated Macrophage (TAM).
The inventors previously reported that memory CD3+CD4+ T cells that encompass large amounts of Treg (Ta-Treg) infiltrated primary breast tumors. Primary breast tumor infiltration by Ta-Treg and plasmacytoid DC (pDC) are both associated with poor prognosis and poor survival of the patient suffering from breast tumors.
The inventors further confirmed that immunosuppressive mechanisms involving Treg are observed in most cancers and chronic infections. These suppressive mechanisms prevent an efficient immune response against cancer and chronic viral infection.
Currently Treg are targeted in cancers and chronic infections using cell therapy, anti-CD25 mAbs or low doses chemotherapy. However, said strategies did not provide acceptable results.
In addition, it has been reported that Treg might have an important role in diseases associated with or caused by an excessive immune response.
However, there is currently no available and efficient strategy for treating Treg associated diseases. There is still thus a great need for providing efficient therapeutic strategies targeting diseases involving Treg.